Immunostaining study of cytokeratins in human hair follicle development

Abstract Background: The hair follicle is a unique structure, one of the most dynamic structures in mammalians, which can reproduce in every new cycle all the mechanism involved in its fetal development. Although a lot of research has been made about the human hair follicle much less has been discovered about the importance of the cytokeratins (CKs) in its development. Objective: Study the immunohistochemical pattern of epithelial CKs during human hair follicle development. Methods: We performed an immunohistochemical study using fresh post-mortem skin biopsies of human fetuses between 4 and 25 weeks of gestational age to study the expression of cytokeratins (CKs): CK1, CK10, CK13, CK14, CK16 and CK20 during human hair follicle fetal development. Study limitations: Restrospective study with a good number of makers but with a small population. Results/conclusion: We found that, the CKs were expressed in an intermediate time during follicular development. The epithelial CKs (CK1, CK14, CK10, CK13) and the epithelial CKs with a proliferative character such as CK16 were expressed first, as markers of cellular maturation and follicular keratinization. At a later phase, CK20 was expressed in more developed primitive hair follicles as previously discussed in literature.

Immunostaining study of cytokeratins in human hair follicle development.

BACKGROUND: The hair follicle is a unique structure, one of the most dynamic structures in mammalians, which can reproduce in every new cycle all the mechanism involved in its fetal development. Although a lot of research has been made about the human hair follicle much less has been discovered about the importance of the cytokeratins (CKs) in its development. OBJECTIVE: Study the immunohistochemical pattern of epithelial CKs during human hair follicle development. METHODS: We performed an immunohistochemical study using fresh post-mortem skin biopsies of human fetuses between 4 and 25 weeks of gestational age to study the expression of cytokeratins (CKs): CK1, CK10, CK13, CK14, CK16 and CK20 during human hair follicle fetal development. STUDY LIMITATIONS: Restrospective study with a good number of makers but with a small population. RESULTS/CONCLUSION: We found that, the CKs were expressed in an intermediate time during follicular development. The epithelial CKs (CK1, CK14, CK10, CK13) and the epithelial CKs with a proliferative character such as CK16 were expressed first, as markers of cellular maturation and follicular keratinization. At a later phase, CK20 was expressed in more developed primitive hair follicles as previously discussed in literature.

Hair straighteners: an approach based on science and consumer profile

Technological progress has allowed women to change their natural hair configuration according to their will. This type of treatment is very popular around the world, even involving the use of prohibited chemicals, such as formaldehyde. Studies of hair characterization, straighteners and toxic evaluation are available in the literature, although few studies have evaluated the consumer profile or the current legislation of Brazil and the European Union (EU) and its influence on the consumption of hair straighteners. Previous studies from our research group have shown that hair care is essential for the quality of life and well-being of women. Within this context, the present study aimed to evaluate the profile of Brazilian hair straightener consumers, as well as the legislation of Brazil and the EU and its influence on the use of these products. The consumer profile was evaluated by applying questionnaires and the legislation was examined using documental and bibliographic exploratory research. The results provided a full understanding of the current legislation of Brazil and its similarities to EU legislation. It was observed that over 50% of Brazilians currently use or have previously used hair straightener products, even persons who do not have curly hair, suggesting that straight hair is more attractive for today's society. Although the study participants consider the current legislation to be important, over 40% do not know the active ingredients present in the hair straightener they use. Finally, the legislation is not considered in terms of the daily hair treatment routine, with the esthetic result being more important to the consumer

Increased rate of hair keratin gene loss in the cetacean lineage.

BACKGROUND: Hair represents an evolutionary innovation that appeared early on mammalian evolutionary history, and presumably contributed significantly to the rapid radiation of the group. An interesting event in hair evolution has been its secondary loss in some mammalian groups, such as cetaceans, whose hairless phenotype appears to be an adaptive response to better meet the environmental conditions. To determine whether different repertoire of keratin genes among mammals can potentially explain the phenotypic hair features of different lineages, we characterized the type I and II clusters of alpha keratins from eight mammalian species, including the hairless dolphin and minke whale representing the order Cetacea. RESULTS: We combined the available genomic information with phylogenetic analysis to conduct a comprehensive analysis of the evolutionary patterns of keratin gene clusters. We found that both type I and II gene clusters are fairly conserved among the terrestrial mammals included in this study, with lineage specific gene duplication and gene loss. Nevertheless, there is also evidence for an increased rate of pseudogenization in the cetacean lineage when compared to their terrestrial relatives, especially among the hair type keratins. CONCLUSIONS: Here we present a comprehensive characterization of alpha-keratin genes among mammals and elucidate the mechanisms involved in the evolution of this gene family. We identified lineage-specific gene duplications and gene loss among the Laurasiatherian and Euarchontoglires species included in the study. Interestingly, cetaceans present an increased loss of hair-type keratin genes when compared to other terrestrial mammals. As suggested by the 'less-is-more' hypothesis, we do not rule out the possibility that the gene loss of hair-type keratin genes in these species might be associated to the hairless phenotype and could have been adaptive in response to new selective pressures imposed by the colonization of a new habitat. Our study provides support for the idea that pseudogenes are not simply 'genomic fossils' but instead have adaptive roles during the evolutionary process.

Elevated formaldehyde concentration in "Brazilian keratin type" hair-straightening products: a cross-sectional study.

BACKGROUND: Brazilian keratin treatment (BKT) and similar straightening products fix and retain a straight shape even when the hair is wet. Unacceptably high concentrations of formaldehyde have been reported in such products. OBJECTIVE: We sought to measure the formaldehyde concentration in all BKT brands marketed in South Africa in 2012. METHODS: We quantified formaldehyde by high-performance liquid chromatography with ultraviolet light detection after derivatization with dinitrophenylhydrazine. All components of 7 identified commercial brands were each tested 3 times. RESULTS: The maximum safe concentration of formaldehyde set by the US Cosmetic Ingredient Review Expert Panel is less than 0.2%. Of the 7 commercial BKT brands, 6 had formaldehyde levels that ranged from 0.96% to 1.4%, ie, 5 times higher than the recommended level; these included 5 brands labeled formaldehyde-free. LIMITATIONS: The study is limited by not including all internationally available BKT products. CONCLUSIONS: Formaldehyde concentrations in BKT products may exceed recommended levels and serve as a health hazard. Industry monitoring is needed to improve compliance and protection of hairdressers and consumers.

Brazilian keratin hair treatment: a review.

Brazilian keratin treatments are widely available products that are used by women all over the world to straighten hair. Marketers of these products claim that the keratin treatments render naturally curly hair more manageable and frizz-free while enhancing color and shine, giving the hair a healthier appearance. Although widely used, there have been virtually no reports of adverse side effects. Unfortunately, many of the products that are applied by salon professionals contain formaldehyde or its derivatives and are being marketed as safe.

Hair follicle stem cell differentiation is inhibited through cross-talk between Wnt/ß-catenin and androgen signalling in dermal papilla cells from patients with androgenetic alopecia.

BACKGROUND: Hair follicle (HF) regeneration begins when signals from the mesenchyme-derived dermal papilla cells (DPC) reach multipotent epidermal stem cells in the bulge region. Wnt/ß-catenin signalling is known to affect mammalian hair growth positively. In androgenetic alopecia (AGA), androgens cause HF miniaturization through a mechanism that remains unclear. Circulating androgens act on DPC and alter paracrine factors that influence hair epithelial cells. OBJECTIVES: To elucidate the role of androgens in dermal papilla-induced differentiation of HF stem cells. METHODS: HF stem cell differentiation was evaluated in a coculture model with DPC or culturing with media conditioned by DPC after activation of androgen and Wnt/ß-catenin signalling pathways. To study the molecular cross-talk between the androgen and Wnt signalling pathway in DPC, we analysed the expression and activation of downstream Wnt signalling molecules in the presence of androgens. RESULTS: In a coculture model with human DPC from patients with AGA and HF stem cells, we observed that androgens abrogate hair differentiation evaluated by hair-specific keratin 6 expression. Wnt signalling activation restored the ability of androgen-treated DPC to induce differentiation. Androgen treatment revealed a significant decrease in the cytoplasmic/total ß-catenin protein ratio and upregulation of the activity of glycogen synthase kinase-3ß in DPC, indicative of canonical Wnt pathway inhibition. CONCLUSIONS: These results suggest that androgens deregulate DPC-secreted factors involved in normal HF stem cell differentiation via the inhibition of the canonical Wnt signalling pathway.

Keratinolytic activity of Bacillus subtilis AMR using human hair.

AIMS: To determine the ability of a novel Bacillus subtilis AMR isolated from poultry waste to hydrolyse human hair producing peptidases including keratinases and hair keratin peptides. METHODS AND RESULTS: The Bacillus subtilis AMR was identified using biochemical tests and by analysis of 16S rDNA sequence. The isolate was grown in medium containing human hair as the sole source of carbon and nitrogen. The supplementation of hair medium (HM) with 0.01% yeast extract increased the keratinolytic activity 4.2-fold. B. subtilis AMR presented high keratinase production on the 8th day of fermentation in hair medium (HM) supplemented with 0.01% yeast extract (HMY) at pH 8.0. Keratinase yield was not correlated with increase in biomass. Zymography showed keratin-degrading peptidases migrating at c. 54, 80 and 100 kDa and gelatin-degrading bands at c. 80, 70 63, 54 32 and 15 kDa. Keratinases were optimally active at 50 degrees C and pH 9.0 and was fully inhibited by the serine proteinase inhibitor (PMSF). Scanning electron microscopy showed complete degradation of the hair cuticle after exposure to B. subtilis AMR grown in HMY. MALDI-TOF analysis of culture supernatant containing peptides produced during enzymatic hydrolysis of hair by B. subtilis AMR revealed fragments in a range of 800-2600 Da. CONCLUSIONS: This study showed that B. subtilis AMR was able to hydrolyse human hair producing serine peptidases with keratinase and gelatinase activity as well as hair keratin peptides. SIGNIFICANCE AND IMPACT OF THE STUDY: This is the first report describing the production and partial characterization of keratinases by a B. subtilis strain grown in a medium containing human hair. These data suggest that peptides obtained from enzymatic hair hydrolysis may be useful for future applications on pharmaceutical and cosmetic formulations.